Controlling the temperature and the lighting within an enclosure, and particularly inside a vessel such as a ship, yacht or boat is often difficult. Without distinguishing between size, or even whether the vessel is primarily intended for fresh-water or salt-water operation, all vessels will hereinafter be designated generically as yachts.
Yachts are almost constantly exposed to the full affect of weather due to the lack of shelter and shade on the water. The interior living areas of yachts, therefore, are often subjected to uncomfortable warming by direct sunlight, especially on cloudless summer days. Sailors have attempted to cool the interior living area of yachts by using various means such as fans and even air conditioners. Yacht builders combat warming by including ports and hatches that selectively allow air to circulate through the interior in an attempt to dissipate heat. Such ports and hatches are also quite often designed to minimize the obstruction of at least outwardly directed visibility. Design limitations such as the shape of the yacht and the limited freeboard above the water line often force the shape of the openings to be non-rectangular.
One inexpensive and effective method of preventing the interior of a yacht from warming is to use coverings in conjunction with the ports in order to control the admission of sunlight. Thus, while solid coverings, akin to window shades, are extremely effective for blocking sunlight, they are generally deemed to be undesirable because they block both airflow and visibility. In addition, a solid covering typically hangs from the top of the opening and can swing and strike against the casing that defines the opening as the yacht moves about one or more of its three primary axes. Such movement occurs as the yacht traverses the waves, as waves strike the yacht, or (depending on the size of the yacht) when people move about on the yacht. The typical multi-axis movement of a yacht creates excessive wear, and undesirable noise, when a covering device simply hangs from the top of the casing in a manner that allows the covering device independently to respond to the movement of the yacht. The covering may also be fastened to the bottom of the casing, but the undesirable blocking of the airflow and sight line visibility remains.
Venetian blinds typically comprise a plurality of parallel, horizontal slats that are suspended one above another so that they may be simultaneously adjusted. Venetian blinds may be adjusted to prevent penetration of the direct rays of sunlight while allowing light to enter. Venetian blinds are also desirable in that they may be readily adjusted so as not to obscure sight line visibility. Venetian blinds typically hang from the top of the casing, and the working parts of the blinds are normally covered by a valance. The working parts, or adjustment devices, generally hang downwardly from the valance.
When the plurality of slats are not connected at the bottom of the casing, the slats slap against the casing as well as the sash in response to the multi-axis movement of the yacht. The adjustment mechanisms also swing freely and slap against the blinds. A further disadvantage to the use of venetian blinds is that they are impractical for use with overhead hatches. When attached to overhead hatches both the "top" and "bottom" are fastened to the hatch, or its frame, and the array of slats bow downwardly. Moreover, the adjustment mechanisms hang freely downwardly into the living area beneath the overhead hatch.